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Nosocomial infection by Staphylococcus haemolyticus and typing methods for epidemiological study
J E Degener1, M E Heck, W J van Leeuwen
1Department of Medical Microbiology, Public Health Laboratory, Leeuwarden, The Netherlands.
Journal of Clinical Microbiology
|September 1, 1994
Summary
A patient with chronic myelogenous leukemia developed a septic episode due to a multiply antibiotic-resistant Staphylococcus haemolyticus strain. Molecular typing revealed related S. haemolyticus strains among hospital staff, highlighting the need for strict hygiene to prevent resistant bacteria spread.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Molecular Epidemiology
Background:
- A patient with chronic myelogenous leukemia (CML) developed a septic episode caused by a multiply antibiotic-resistant Staphylococcus haemolyticus strain during cytostatic therapy.
- The S. haemolyticus strain exhibited high minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for vancomycin and teicoplanin, critical last-resort antibiotics.
Observation:
- A surveillance study investigated S. haemolyticus carriage among medical and nursing staff in the patient's hospital ward.
- S. haemolyticus was isolated from 18 sites on 12 of the 39 healthcare personnel tested.
- Molecular typing methods, including immunoblotting, plasmid analysis, restriction fragment length polymorphism (RFLP), and pulsed-field gel electrophoresis (PFGE), were employed to analyze isolates.
Findings:
- Molecular methods proved more discriminative than immunoblotting for differentiating S. haemolyticus isolates.
- While the patient's colonizing strain showed consistent patterns, molecular techniques found no evidence of its local spread among staff.
- However, plasmid profiles, RFLP, and PFGE indicated relatedness among S. haemolyticus isolates from hospital ward personnel, distinct from unrelated sources.
- RFLP analysis was more discriminatory when using IS431 as a DNA probe compared to the 16S rRNA gene probe.
Implications:
- The emergence of vancomycin- and teicoplanin-resistant S. haemolyticus poses a significant threat, as these are crucial for treating nosocomial gram-positive infections.
- The relatedness of S. haemolyticus isolates among hospital staff underscores the potential for local spread of multidrug-resistant organisms.
- Strict adherence to hygienic measures and judicious antibiotic policies are essential to prevent the dissemination of such resistant strains within healthcare settings.